Just found a good deal on the air filter housing seal 2720940080. I typically follow the Mercedes maintenance manual and it says replace the air filters every 40,000 miles/4yrs. (cabin air filters every 20,000 miles/2yrs). But I clean and inspect them at least once a year, once after winter as part of a spring cleaning and then around fall getting the car ready for winter. Ill remove the air box and give it a thorough cleaning, ill even vacuum out the filters. I noticed the rubber seal looks a little deformed and I feel all this removing and reinstalling has to wear the rubber down. I still want to replace the further down where the maf sensor mounts to the elbow and then the seal at the throttle body.

Previously the "clamping piece" part# 340 in the diagram fit loosely and would move around on its own, then I decided to clean the maf and elbow below it and after putting everything back it then snapped on solid over the air box. It must have not been put together properly before.

Seal was only $7.99 free shipping, which is why I think its a good deal. Ordered it the 17th and got it today the 21st. Local Mercedes dealer wants $8.75 and would have to go pick it up.

I just checked my 3yr old cabin air filter and the thing looks very good. Got out my vacuum and stuck it all in between the pleats. I see no reason to replace it yet. I never use the ac, always just have the sunroof and windows open. Only time I use the climate control is winter for heat.

 

I have some free time so im messing around with the air cleaner. Took it off to inspect and clean the air filters. I write the install date so I dont forget and they are around 2yrs old, dont look bad at all. Banged out the dirt and dust in the sink then gave them a good vacuuming. Put the new seal on and it fits great. The old seal feels a bit harder but probably didnt need to replace, but it was cheap so happy I did. Its probably all in my head but im feeling the car will run that much better now. Plus I love cleaning things. I always wondered why the white filters in the air box, wonder if it has to do with it being a PZEV? Odd they cannot be replaced.

Figured id make this post for myself so i can keep track of what and when I do things to the car.

 

The retainer fits even better now. When I first got the car I noticed it was very loose, did not "snap" on at all. Then I removed and cleaned the maf sensor and elbow below and after putting everything back it seemed to fit better, it would actually catch. I was wondering if everything was put back properly previously before i got the car. But now im using both hands to snap it on and remove it.


This kind of reminds me of the dip stick, where when I got the car it felt like it was just dropped in there and could be pulled out very easily. Then i replaced the oil filter and replaced that o-ring with one that came with the Mann oil filter and now it snaps in solid and it takes some effort to pull it out.

 

With some more searching about what those white charcoal type looking filters are im going to say they are part of the Mercedes air cleaner Integrated Hydrocarbon Trap. I found this term in the PZEV warranty in my operators manual. Ive read that these filters, or traps, are installed between the air filters and the engine to absorb hydrocarbons that can leak out while the car is off. So far im not finding much information searching for Mercedes Integrated Hydrocarbon Trap but came across an article from BASF that talks about hydrocarbons and air filters.

https://www.basf.com/us/en/media/new.../p-13-477.html





Then I came across a 2007 paper that mentions "evaporative emissions device" to be permanently installed in the air cleaner without requiring service for 150,000 miles. So what happens after that is my question now. I dont think it really effects air flow since the filter is just trapping gas, and when activated charcoal is full it seems to just stop working.